Collapsible wall type expansion engine



1952 J. R. AVERILL COLLAPSIBLE WALL TYPE EXPANSION ENGINE 3 Sheets-Sheet1 Filed Aug. 51, 1950 lllllllllllllllllllllllllllllll I A A A IINVENTOR. JOHN 1?. 44/15/7141., By wk flaw ATTORNEYS,

Jan. 8, 1952 J, R AVERILL 2,581,830

COLLAPSIBLE WALL TYPE EXPANSION EZNGINE Filed Aug. 51, 1950 3Sheets-Sheet 2 INVENIORK' 'dH/Y MER/LL,

RTTORNE'YS.

Jan. 8, 1952 J. R. AVERlLL COLLAPSIBLE WALL TYPE EXPANSION ENGINE 3Sheets-Sheet 3 Filed Aug. 51, 1950 e L a z. 0 c u/ M i M} k M m Y & llllk t 'IIIIIIIIIII IN VEN TOR. J aH/v' I 40/52 11 L 9c Z A T To RN EYS.

Patented Jan. 8,

- coLLArsiBLE This invention relates to of the rotary type, wherein agas is introduced into the engine at an elevated pressure and dischargedtherefrom at a lower pressure. The expansion of the gas in the engineimparts rotary motion to the shaft of the machine, and thus converts theenergy which is released by the gas into useful work. The expansionengine of the present invention is particularly useful where the gas,which is used as a source of energy, is accompanied by, or is dissolvedin a liquid, The expansion engine of the present invention is useful notonlywhere the. primary consideration is the generation of power,but-also wheresthe primary consideration'isthecoplinghfihegas passingthrough themaehine, The expansion engine of the present invention isparticularly useful in connection with flowing oil wells where gaseouscompounds emergedn various proportions along. with the oil. Generallyspeaking, in such oil wells there is no sharp distinction between thegaseous and liquid components. Usually, there is an intermediate groupof hydrocarbons which may remain in the liquid phase or evaporate intothe gaseous phase, depending upon the conditions an expansion engine '17Claims. (!;121-48)" which are present. These components are charbeingproduced. The maintenance of a high gravity in the oil produced is verymuch to the producers advantage because the oil will bring a higherprice per barrel. A loss of gravity as through heating, will, of course,reduce the price I per barrel and also involve a loss in volume of oilproduced. The lower the temperature at which the gas and oil can beseparated, the more of the valuable light ends can be retained in theoil so that the oil will bring the highestprice.

, Various procedures have been utilized in the past to retain more ofthe light ends dissolved in the oil, and among these has been adiflerential method of separation, wherein the pressure is reduced inseveral stages and volatilized gas is removed from the oil at eachstage.

-- Where a straight throttling'type of expansion.

is employed, the separation takes place at a relatively hightemperature. If an. engine'is' pro? vided to take energy from theexpanding gases and do external work while reducingtlie pressure of thegas-oil mixture, 9, lower temperature.

of the outgoing product can be obtained than is to conserve the lighterends; and be beneficial from that standpoint, entirely aside from thevalue of the work performedby the engine.

Conventional expansion engines of the reciprocating or turbine typeswould not be feasible for this work because of the waxes and othersolids or semi-solids which are present in most oils, which upon beingcooled would build up deposits in flowlines and-stock tanks, and wouldrequire heatingof the production rather thancooling so asto avoidcomplete plugging of the, lines and equipment. Thus, any of the familiartypes of expansion engines would quickly be fouled by these deposits andsuch an operation would be impracticable. q With the foregoingconsiderations in mind, it is an object of the present invention toprovide an expansion engine,.which will be self cleaning in nature, sothat the solids and semi-solids which would comeout of solution oncooling, would be separated out without in anyway fouling the engine. Itis an ancillary object to provide an engine wherein the precipitation ofthese materials within the engine, rather than in the flowlinesdownstream, is encouraged. It is another object of the'invention toprovide; an engine which" will minimize the contact of liquid andgaseous components during evaporation and expansion of the gas phase,and which will have a-tendency to produce a recondensation of theheavier fraction of the gas phase and return it to the liquid phase.- WI It is still another object of the invention to provide an engine asabove outlined, wherein foaming during reduction of pressure will beminimized,-whereby the gas and liquid may be piped off the engineseparately thereby eliminating the needfor an external separator. v 1

Other objects of the invention include the provision of such an engineof comparatively simplicity, and the provision of a rotary positivedisplacement engine with uni-directional flow of expanding gases. Theseand other objects of the invention, which will bev set? forth. inmoredetail hereinafter, or which will be apparent from a study of thespecification I accomplish by that certain construction and arrangementof parts of which I shall now disclose certain exemplary embodiments.Reference'is made to the drawings forming a part here of, and in which:Figure 1 is'a horizontal cross sectional view through an expansionengine according to my invention, taken on the line 'l of Figure 2,

Figure 2 is a vertical cross sectional view of the same taken on theline 2-2 of Figure 1,

Figure 3 is a fragmentary cross sectional view similar to Figure 2, butshowing the parts in the position which they occupy after a quarter turnof the hub,

Figure 4 is a view similar to Figure 3 showing the position of the partsafter a half turn,

Figure 5 is a view similar to Figure 4 showing the position of the partsafter three-quarters of a turn,

Figure 6 is a view similar to Figures 3 to 5 inclusive-iotamodifieddevicag- Figuregl is a. view similar to; igur yet anothermodification,

Figure 8 is a view similar to Figure 1 of another form of expansionengine,

Figure 9 is a cross sectional view of the same taken on the line 99 ofFigure- 8, V

Figure 10 is a cross sectionalvielw ofa modified engine, taken on theline Ill-l0 of Figure 11,

and

Figure 11 is a cross sectional view of the same, taken on the line llllof Figure 10.

Briefly, in the practice'gof my invention in its simplest form, Iprovidef a casing in which is mounted a flanged hub. flhe hub isprovided with an axial passage, and a. radial port comni'unicateswiththeaxial passage. impel vio'u's strip of. "flexible materialffsuch. asspring biojr'ize orthe like',.i's'securedat its one endto the 15 0,,preferably immediately behind the. port (in trr'iisf., of I theIdirectionfof rotation .of .the hub) and is loosely wound around-the hubbetween the flan es." sqfthatits free.,end'. trailsin terms oftheldirection f retained the 11115;: ,The flexible strip; islof suchwidth that mean slide. freely betweenfthe' flanges" andjyet .m'aintain.a'seal to pieverit' leakage .of' fluids, around ,the edges, and atjeastofsuc'h a lengthjthatit can form one tight vconvolution,abou 'tthei"hub,' and another convolution of a diameter. substantiallyequal tothe'radiu Of the flanges plus theradius of the hubf 'The' s'tripf can,of course, be. of greater length'as will be described hereinafter. Meansare prhvi'ded" for, pressing .j the ."strip against the hub at onepoint, and such'me'ans may" comprise awheel of a. width to.,fit betweenthe-flanges and-b ar Iaga'in tthe fstrip, oriiith m a s may comprise awhich will fitI-betweent'he flanges and .bearj 'again'st .the strip. If.a ring i'su'sed. a wjhel must" be provided opposite the hub to maintainthe'f'r'i'ng in its. operative position. It will'b' understood thatasu'itabIe stufling'l box is provided in connection withfthegaxialpassage ihthe hub and the gas or. gas oifmixtureenters the, axial"passage by wa'y, .of. a suitable stufiing a ast e t-c vent ne a ds, Tha ratio i such, tha maths-t me P1 01 ex n o its erm tteiiz r M lat it ed hugsyfficiently to rotate ,one turns Qne-turnof theflan :huhsha rms,-t nn r s n emand g vides a n wmmn rtm ntwfor 1nemin fifldstehork a ai stbefo e the outer end or free end of the strip slides under the point ofcontact, between the hub and the wheel or ring, and releases theexpanded fluid which entered during the first revolution. With each turnof the flanged hub shaft, the cycle is repeated. The energy of theexpanding gases is thus converted to rotary motion of the shaft, and thepower obtained from the expanding gases in excess of that required toturn the engine itself can be taken off one of the shafts to performuseful external work. In order that the lowest temperature and maximumcondensation of the outgpingproducts-gbe attained;;this;power should betaken err. andjdissipated outside .the'. machine.

Referring now more particularly to the drawings, I have shown in Figure1 a casing l0 within which the Working parts of the engine are Imounted. The casing I0 is provided with bearing bosses II in which isjournaled a shaft [2, having a hub l3. Flanges l4 are secured to bothends of the hub. A suitable stuifing box arrangement, generallyindicated at l5, may be secured to the casing ID by means of a bracket[6, but the particular stuifing box will not be described in detailsince it forms no part of the present invention. The portion of theshaft l2, which extends into the stufling box [5, is provided with anaxial passage I1 which communicates with a radial port l8 in the hubproper. A supply line 19, provided with a suitable valve 20,communicates with the end of the shaft [2 and the passage Secured to thehub I3 is an impervious flexible strip 2|, which may be of spring bronzeor similar material- One end of this strip 2| is secured to the hub asat 22, preferably immediately behind the port I8 in terms of thedirection of rotation'of the hub. The strip 2| is of a width to fitsnugly between the flanges I4 and is of a length at least suflicient toform one tight convolution about the hub l3 and one additionalconvolution of a diameter equal substantially to the radius of theflanges plus the radius of the hub as clearly seen in Figure 2. Thestrip is Wound around the hub in the opposite direction to the directionof rotation of the hub so that its free end 23 trails in terms of thedirection of rotation of th hub.

In the embodiment of Figures 1 to 7 inclusive, another shaft 24 isjournaled in bearing bosses 25 in the casing l0 and the shaft 24 carriesa wheel 26, which is of a width to fit freely between the flanges M ofthe hub l3. As clearly seen in Figures 1 and 2, the wheel 26 bearsagainst the strip 2| and holds it against the hub I3. The shafts l2 and24 are geared together by means of a gear 21 on the shaft 24 and thegear 28 on the shaft l2. Thus the two shafts are geared together torotate in opposite direction at a fixed ratio to each other. This ratiois chosen such that the peripheral speed of the wheel is greater thanthe peripheral speed of the hub, so that a shearing action is set up onthe strip between the wheel and hub. This shearing action results inslippage between the loops of the strip and between the strip and thehub, with preferably no slippage between the wheel and the strip. Thematerials of the strip and wheel are selected with a view. to obtain amaximum coefficient of friction between the wheel and the strip. Underideal conditions, therefore, the peripheral speed of the wheel and theperipheral speed of the outer convolution of the strip are the same.Since the peripheral speed of the hub, the greater speed of the wheelwill cause the strip to belly out from the hub everywhere except at thepoint of contact as the shafts rotate. The ratio of the gearing betweenthe two shafts will be the same as the ratio of the wheel circumferenceto the maximum outer loop circumference of thestrip, ,provided there isno slippage between wheel and strip. In :actual. practice, there will besome slippage at the point of.contact,"the strip will move somewhatfaster peripherally than the wheel when fluid pressure is applied at theinlet port 18, and the maximum outer loop will be correspondinglyenlarged. The maximum outer loop, under operating conditions, shouldstill be entirely retained between the flanges 14.

eccentric 30 on the shaft I2, and a follower stem 3| slidable in thebearings 32' and 33 and having a follower 34 riding on the eccentric 30.An arm 35 secured to the rod 3| may operate the valve lever 36 which isurged in a clockwise direction by the spring 31. A manual throttlingvalve may be provided at 20a for adjusting the quantity of admittedfluids to control speed and/or power output of the machine. It will beunderstood that various valve operating mechanisms could be provided,and that fluid can be admitted at any desired stage of rotation of thehuband may be cut oil at any desired stage of rotation so that furtherpower is achieved through expansion -of the gases. The machine willoperate without the cutoff type of valve as described above. A simplethrottling valve in the inlet line would be the minimum requirement,allowing fluids to enter during the entire 360 degrees of rotation ofthehub. Speed and power output would be governed by pressure drop acrossthe valve. Full line pressure downstream from the valve would be on theexpansion chamber throughout the cycle. This'would be permissible in aliquiddriven machine but would be undesirable in a gas-driven machine inthat expansion of the activating gas could not take place within themachine. In a 'multi-stage machine to be described, however, the initialstage could operate .at line pressure with expansion taking place insubsequent stages.

As best seen in Figure 2, a ,g'tasasoutlet is indicated at 38 and aliquid outlet a For a better understanding of the operation of theexpansion engine, Figures 2 to inclusive may be considered together. Inthese four figures the hub I3 is shown at 90 intervals in itscounter-clockwise rotation. Thus, in Figure 3, gas or thegas-oil'mixture entering through the line I9, the axial passage l1 andthe port I8, enters the crescent shaped space between the hub and theinner convolution of the strip 2|. As the gas enters it pushes the stripaway. from the hub which causes the strip to slide past the "hub at thepoint of contact with the wheel 26, and therefore, causes the wheel 26to turn.

Since the wheel 26 is geared back to the hub l3, the hub I3 is caused toturn and to reform a small coil tightly around the hub as the first coilexpands. As pointed out above, the gear ratio between the gears 21 and23 is such, that by the time the outer convolution has expanded to itspermitted maximum size, it will have turnedt-he wheel a sufficientamount to causethe shaft .12 and hub l3 to rotate one turn. Thus,when-the shaft l2 and its'hub' l3 have completed one revoapensso Ilution, the inner coil has been reformed to the position shown in Figure2. At this point the crescent shaped chamber has achieved its maxi mumsize, and as soon as the hub has turned slightly more in acounter-clockwise direction to free the end 23 of the strip from betweenthe hub l3 and the wheel 26, the gas and the liquid within the crescentshaped chamberare'free to pass into the casing ID. This .is a positionwhich would occur immediately after the position of Figure 2 and justbefore the position of" Figure 3.

The liquid components will accumulate against the point of contactbetween the strip and the hub by the motion of the flanges andthe stripand these liquid components will be held at this point until the nextrevolution when the free end of the strip passes the p'oint of, contactand releases them. Wh'en'the liquid components are released, they passaround or under the wheel and are thrown ofi .by centrifugal forceagainst the walls of the housing from where they flow downwardly to bepiped off through the line 39. The gases, of course, are removed throughthe line 38. Thus the housing serves as a separator and separates thespent gases from the liquid phase without foaming. v

As for the solids and semi-solids (hereinafter called waxes on accountof their plastic or mushy physical appearance when precipitated) whichmay accompany the gas-oil mixture, these may precipitate in theexpansion chamber. Whether they precipitate on the flange walls or onthe strip, they will gradually be transported to the point of contact ofthe strip and hub and the waxy precipitation will assist in maintaininga seal between the sliding contacts against the escape of expandinggases during this operation. The wax which accumulates at the point ofcontact is pushed along the strip to its end and may either be permittedto be discharged along with the oil phase, or it may be separatelycollected L as will be described in connection with another embodiment.Because of the low temperature of the liquid when it emerges from theexpansion engine, wax solubility will be at its lowest and the wax will,therefore. be precipitated within the expansion chamber to its optimumdegree. If equilibrium conditions are attained within the expansionchamber, further deposition of waxy materials will be impossible.

The principle discussed herein above can be extended to multi-stageoperation. Thus, if the length of the strip is increased, it may formseveral coils aroundthe hub, and this is advantageous if completeprecipitation of the wax in the expansion chamber is important. Thus,for example as shown in Figure 6. if the strip 2m is twice theminimumlength set forth above, it can provide four convolutions aroundthe hub so as to give three expansion chambers in series instead of asingle expansion chamber. In this way, an entering charge of highpressure fluids will remain in the expansion system for threerevolutions of the hub instead of one. In this way, the oil from whichthe wax precipitates will contact more coil area for a longer period oftime, and a closer approach to equilibrium conditions is attained thanwould be possible in a single stage machine. Furthermore, the fourconvolutions of the strip provide additional sealing area, so that thereis less pressure drop across each line of sealing contact between thestrip and the flanges and consequently, there is less overall leakage.Furth'ermore, the same amount of slip at the point of contact is dividedbetween more-:surfaces @so..-.:that; friction witlrinzthexmachine:decreased. .It will have to be: borne mind-that theadditionaldeng-th .of"strip will, of, course, provide? more;;drag aagainstaithe. flanges,which; would-r-tendwd offsetlthe;advanta esjof decreased frictio'n:-Additional advantages are provided by: multiestage operation. In ?thefir'st place, .theres-is. atendency: toward .a; differential type-ofseparation-oi gasrfroin' oil, and secondly; thereis a tendency 'toacontinuously condense and returnzto .the liquid phase the heavier fracliQ $:.Qf'-,the* gaseous phase: vBoth or: these results-are beneficial.to: the.zproducer' becausexthey as st in retainin -a maximum' amount:of the l h t nd zofztheproduction .in tl1e3va1uable liq uid phae-rather thanzin: the lessrxialuable'gas eons; phases? -An additionalbenefit :will be found in-a reductiomof .thet'emp'erature of theexhaustfluids by the removal of additional energy during expansion.-

'3 1 r To clarify what is meant by difierential sep-' aration, a batchtype of distillation may be cited asexemplary. Thegas phase'is:continuously removed from contact with the-liquid phase as fast asitis., formed. This inherently-*results.in a more complete separation of:the lowest boiling components, and a more complete retention of theintermediate fractions in .the -final liquid phasethanv-can beattainedby a'fiash' type of reduction, which may beexemplified by theconventional practice of flashing the production of a-well through anrorifice to'redu'ce the pressure. In, the .-mu-lti-stage expansion:engine described above,- while the-liquidand gas phases remain thesamecompartments.xduring the J entire expansion, they are segregatedbythe motion cf. the; machine.-- .The expansion chambers, as clearlyseen in the drawings, are crescent shaped with'the horns of thecresentto either side of the point-0f contact with .the hub. The motion of themachine-in rotation tends to draw the liquid components into the horn ofthe crescent, which isapproachingthe point of contact, while the gasphase will-,pccupy theremainder of the expansion; chamber..Thus-,"the1"e::. is; very little liquid surface-exposed to the. gas,although the liquid is held a state of 5 rather violent agitation by thecoils of the strip as .they .slide past the .fiuid and under thepoint-,oficontact. 'Since -there is little surfaceexposed, there is.little chance for the gas, which-has been liberated,- to recontacttheliquid at lowerpressure, and this -condition, therefore, approaches thatof a true differential separation. 1

"The. ractionating action which has beendiscussed, arises from the .factthat each expansion chamberfis cooler than the adjoining inner ex-,pansion' chamber and warmer than the adjoining :outer expansion chamberThe-fluid inan ex? pansion chamber-will tend to cool the inner convexwall of its} chamber and be -cooled by the outer'concave'wallofitschamber the coolingaction onthe 'conca .i surface is suflicient-toliquefy any'lof the heaviencornponents of the gas ,phase the lcondensate willf be transported by L movemerit'of the'str f -up tothepoint of contact where it will rejoifizthe liquidiportion of thefluids. 'jln figure .7 1, haves hownl a modification wherefin twos'trips are-attacHed tothe 'hub with en.- tra'nce ports undereach striphisgprovides for ,expansion'stag'esin p'aral'lelas I l-as,, expansionls'tage's series, an it .the tivating fluid is Iintroducedin two" or meincrementslpeij revoluf- 'n ill resu1t, Friction Wee-. the. stri s -i yindicated at 21a.

avera e be treduced' nsi ez-st -ibsc dissi lar m teriat The sam i adanta e.- emayi. of course, e; gai d by :the use of a;. singlestrip-having; dissimilarsur; faces. yllletwo strips ',in Figure .17 .areindicated at .-2 lb and 2- .0. and .the ra po s are icated 1: .Stillanother-mod fication of the expansioneninegisshown in-Figures Band 9,,The principles employed in the device of'Figures-8 and,9 'aresubstantially the same asthose discussed above. except. that instead, ofaconvex surfaccof revolutionzto hold'the convolutionsof the stripagainst thehub; I: have shown the use ofa concave surfaceiiof revolution:in the ,form of. a ring. In thr device of Figures-8 and 9; a casingisprovided at -l ll a and a shaft 12a is mounted-in suitable bearingsHa. ,Theshaft .1 la carries a hub |3a;hav..- ing an-axialpassagel1,a,.and in this-instance, two radial. ports 18c; A-strip of flexiblematerial similar tothose described above is indicated at Zld. H

Instead of using a wheel 26 as described inv connection with Figures 1to 7 inclusive, I employ a. ring 26a providing a concave surface ofrevolution to bear against the convolutions of the strip and to pressthem-against the hub I 3a. The ring is held in position, byan additionaldisc 26b mounted on a shaft 24a, mounted in bearings 25a. In Figures 8and 9 I haveillustrated the shafts ua and [2a as being geared togetherby belting, The hub 13a is again provided with flanges Ma and thestrip21b is of such a width as to fit snugly between the flanges Ha, whilethe ring26a fits loosely between the-flanges as clearly seen in Figure8. The belting 2.1a is arranged so that the shafts l2a and 24a rotate inthe same direction whereby the ring 26a also rotates in the samedirection. The speed ratio is determined, again by the circumferencedesired of the outer loop of the coil against which the ring 26a bears.The ratio of the circumference'ofthe outer loop to the circumference ofthe wheel 26b will have to be the same as the-ratio of the pulleysthrough which the shafts l2a and 24a are belted together. In theembodiment of Figures 8 and 9 I have shown three connections to thecasing. The connection 38a serves for the removal of the gaseous phase,as in the embodiment of Figures 1 and 2, while the connection "39 is forthe removal of the liquid phase as before. Another fitting 3% serves.for the removal f'of the wax, which will be collected off the strip 2 Idon to the wheel 26!), whence it is scraped off by the scrapgrjo. The waxcollecting on the surface of the wheel. 26b will, by contact.with thering 26a, be squeezed out toward the side faces of the wheel 26b and thescraper 50 removes the wax from the side faces of the wheel 26b. InFigure 8 -I have shown a power takeoff pulley at 29a mounted on theshaft l2a, whereas in th embodiment of. Figures 1 and 2 power is takenoff the .shaft 24. While power may, of course, be taken off eithershaft, the-arrange mentof Figures 1 and 2 is preferable because then thegearing or belting between the two shafts iscalled upon totransmit lesspower than in the embodiment of Figures 8 and 9.

Q {is far as dimensions are concerned, it may be pointed out the maximumexpansion space is obtained when the flanges M or Me are of a diam=eteri' approximately three times the diameter of ,the hub I 3 or I 3a..Also, it may be noted that within the limits offiexibilityof thestrip,,the wider the strip isthe better the operation will be he reasonfor this is that a wide strip :will

.-but'.-will .cojntaini a larger gvoluiiije of revolutionhave relativemovement;

have the same length of 'sealingaa a -narrow. strip. er expandin gasesforth'e same sealing 'areal' 1 7 9 fo a -d rees 1 1 ;e ei i J ,bodimentsof the invention. {whe in' l the .two

In some instances it maybe defable to have the hubnon-rotatably mountedirrthe casing and to provide means whereby the 1i; oi -c es between thehub and surface of revolutiom-moves n a; tar rb t; @ibQ i 2.-,- rh ibj 71 5.- in

- n m od m n h ii faceeo t qlufi n ma 'b -co ti t d-b aw ee w ii har rqih outside of the -hub to; pr ess -th xible strip a a ns e b- :3. a v v Ts a be a omp sh d anv arran eme whereby the secondshaftfimayiravel.orbitally aboutrthe hubshaft in the casing. Thus inFigures 10 and 11 I have shown an arrangement wherein the shaft 12b: isfixed tot the casing lllb by welding, brazing or other suitable means,as at illc. Thus the shaft I21) and the hub l3b are stationary withrespect to the casing lllb. The hub is provided with flanges Mb asbefore and a flexible strip He. The hub has the axial passage 1 1b andthe radial port l8d. Valves b and 200 are provided for the passage "band correspond to the valves 20 and 20a of Figure 1.

In this instance however the wheel 26b is mounted in bearings 60 and 6|.The bearing 6| is at one end of an arm 62, the other end of which isjournaled by means of a bearing 63 about the shaft I 2b. The bearing 60is mounted on the end of an arm 64 which is integral with or secured to.a stub shaft 65 mounted for rotation in a bearing and stufiin'g box 66and provided with a pulley 61 for power take-off. The member 65 has aninternal bearing at 68 by means of which it rides on the end of theshaft l2b. Thus the wheel 26b, together with the arms 62 and 64 and themember 65, rotates so that the wheel 26b moves in a planetary orbitabout the hub l3b. Therefore the point of contact between the hub andthe strip moves in a planetary orbit about the hub.

As before a gear 21b is provided on the shaft 260 and a gear 210 issecured to the shaft I212. The ratio of these gears is again chosen toprovide the peripheral speed ratio between the peripheral speed of thewheel 23b and the peripheral speed of the outermost convolution asdiscussed above.

In Figures 10 and 11 a slightly different arrangement for actuating thevalve 20b is provided. A lug 10 on the arm 62 projects into the path ofa lug ll secured to the valve stem 12 rically spaced about the peripheryof the hub l 3b.

It should also be noted that the apparatus will work Without a casing,since the expansion chamber or chambers are provided between the flangesand the convolutions of the flexible strip; nevertheless, forconvenience as well as for a pearances sake, I prefer to provide acasing as shown.

It will be understood that numerous modifications may be made without dearting'from the spirit of the invention and therefore, I do not intend.;to limit myself in any manner other than as pointed out in the claimswhich follow.

Having now. fully described my invention, what I claimas new and desireto, secure by Letters -.Patent is:

1. Am ,expansion engine comprising a flanged hub, an axial passage insaid hub and'a radial port .in said hub communicating with said pas-,.sag,...an impervious strip of flexible material, of

substantially the width of said hub between said ,flanges, secured atone of its ends to said hub, .and loosely wound around said hub so thatits free end trails in terms of the direction of 1'0- tation. of saidhub, said strip being of a length at leastrsufiicient to-form oneconvolution tightly around saidhub plus an outermost convolution of.a-diameterssubstantially equal to the radius of the flanges plus theradius of said hub, a surface of revolution contacting said strip infrictional driving relation and pressing it against said hub, --meansforproducing relative rotation between said hub and the point of contactbetweensaid :hu-b andsurface of revolution, said volution tightly aroundsaid hub, a plurality of convolutions of progressively increased size,and an outermost convolution of a diameter substantially equal to theradius of the flanges plus the radius of said hub.

4. An engine according to claim 1, wherein an enclosing casing isprovided, said casing having a liquid iischarggport and a gas dischargeport.

5. An engine according to claim il'wherein said flexible strip is of alength to form one convolution tightly around said hub, a plurality ofconvolutions of progressively increased size, and an outermostconvolution of a diameter substantially equal to the radius of theflanges plus the radius of said hub.

6. An engine according to claim 5, wherein the surface speed ratiobetween said hub and said surface of revolution is substantially equalto the ratio between the circumference of said hub and the maximumcircumference of said outermost convolution. so that when said hub makesone revolution with respect to said point of contact, said outermostconvolution also makes one revolution with respect thereto.

'7. An engine according to claim 5, wherein scrapingmeans are associatedwith said surface ""of' r'evolut id'n to remove waxy precipitatetherefrom, and separate outlet means in said casing for said waxyprecipitate.

8. An engine according to claim 1, wherein said surface of revolution isthe outer surface of a wheel, and the peripheral speed of said wheel issubstantially equal to the peripheral speed of said additionalconvolution.

9. An engine according to claim 1, wherein there is provided in saidhub.an additional radial port, and in which a second impervious strip offlexible material is secured to said hub in the Same relation to saidadditional radial port Max:

11 as said first mentioned strip is secured with regard to said firstmentioned radial-port, 10. An engine according to claim 9,.whereinscraping means are associated with said surface of revolution to removewaxy precipitate therefrom, and separate outlet means in said casing forsaid waxy precipitate.

11. An engine according to claim 1, wherein power take-oil means areprovided in connection with said surface of revolution.

12. An engine according to claim 1,- wherein a valve is associated withsaid axial passage, 0 rein means are provided to actuate said valve intimed relation to the rotation of said hub with respect, to said pointof contact.

13. An engine according to claim 1, wherein said surface of revolutionisthe inner surface of a ring.

14. An engine according to claim 13, wherein said ring is supported bysaid hub and by a wheel, said wheel and the inner surface of said ringbeing also in frictional driving relation, the other side of said wheelbeing infrictional to remove waxy precipitate therefrom, and separateoutlet means in said casing for said waxy precipitate.

' 17. An engine according to claim 1, wherein said surface of'revolution is the outer surface of a wheel, and wherein said hub isfixed and said wheel is mounted on arms journaled with respect to saidhub, so that said wheel and its point of contact with-the hub movesaround said hub in a planetary orbit.

QH .Rt AVE L No references cited.

